It has been estimated that at least two days of laboratory time and the use of fluorescent labels are required to assess cellular changes upon exposure to biological entities. See, e.g., Dharmawardhane et al., 1997, J. Cell Biol. 138(6):1265-78. Additionally, it has been estimated that at least 8-24 hours of laboratory time and the use of a secondary dye are required to quantify total cell movement or cell changes toward biological entities, such as a protein, peptide or small molecule. See, Reckless & Grainger. 1999. Biochem. J. 340: 803-811, Taguchi et al. 1998. J. Exp. Med. 187(12): 1927-1940, Jackson et al. 1999. J. Pharm. & Exper. Therapeutics. 288(1): 286-294 and Yarrow et al., 2004 BMC Biotechnol. 4(21):1-9.
Monoclonal antibodies are produced by hybrid myeloma or hybridoma cell lines (referred to herein as “hybridomas”). Screening of hybridoma supernatants for antibodies that specifically bind a protein target is a critical step of monoclonal antibody production. Many thousands of myeloma cells and mouse spleen cells are fused together and grown together in HAT selective medium. Only hybrid cells containing the DNA of both types of cells are able to grow and therefore produce IgGs. The supernatant of the mixture of these cells is screened to determine if any of the cells in the mixture produce an antibody that specifically binds a protein target.
ELISA assays can be used for the screening of this complex mixture of antibodies. However, ELISAs are time consuming and are often qualitative. Additionally, an isolated protein used to capture the antibodies on an ELISA plate may not appropriately mimic the true protein found, e.g., on the surface of a cell. The isolated protein may have a different folding conformation, be situated on the ELISA plate so that parts other protein are not available for binding to antibodies, or have any number of other sterically or chemically related inhibition issues. Antibodies identified using ELISA screening may have very little affinity for the natively folded protein on, e.g., a cell surface. Unfortunately, this information will not be apparent for several weeks. Furthermore, antibody selection processes are not able to discern specific desired biological activity against the target by antibody binding until late in the process in other complex assay formats. Methods are needed to reduce the time to perform these assays.